negate.cpp revision 4f1efc098cb5791c3e9f483f2af84aef70d2d0a0 
1/* ------------------------------------------------------------------
2 * Copyright (C) 1998-2009 PacketVideo
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
13 * express or implied.
14 * See the License for the specific language governing permissions
15 * and limitations under the License.
16 * -------------------------------------------------------------------
17 */
18/****************************************************************************************
19Portions of this file are derived from the following 3GPP standard:
20
21    3GPP TS 26.073
22    ANSI-C code for the Adaptive Multi-Rate (AMR) speech codec
23    Available from http://www.3gpp.org
24
25(C) 2004, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC)
26Permission to distribute, modify and use this file under the standard license
27terms listed above has been obtained from the copyright holder.
28****************************************************************************************/
29/*
30
31 Pathname: ./gsm-amr/c/src/negate.c
32
33------------------------------------------------------------------------------
34 REVISION HISTORY
35
36 Description: Created separate file for the negate function. Sync'ed up with
37          the current template and fixed tabs.
38
39 Description: Removed conditional code that updates WMOPS counter
40
41 Who:                       Date:
42 Description:
43
44------------------------------------------------------------------------------
45 INPUT AND OUTPUT DEFINITIONS
46
47 Inputs:
48    var1 = 16 bit short signed integer (Word16) whose value falls in
49           the range : 0xffff 8000 <= var1 <= 0x0000 7fff.
50
51 Local Stores/Buffers/Pointers Needed:
52    None
53
54 Global Stores/Buffers/Pointers Needed:
55    None
56
57 Outputs:
58    var1 = negated value of input (Word16)
59
60 Pointers and Buffers Modified:
61    None
62
63 Local Stores Modified:
64    None
65
66 Global Stores Modified:
67    None
68
69------------------------------------------------------------------------------
70 FUNCTION DESCRIPTION
71
72 This function negates var1 with saturation; saturate in the case where input
73 is -32768: negate(var1) = sub(0,var1).
74
75------------------------------------------------------------------------------
76 REQUIREMENTS
77
78 None
79
80------------------------------------------------------------------------------
81 REFERENCES
82
83 [1] basicop2.c, ETS Version 2.0.0, February 8, 1999
84
85------------------------------------------------------------------------------
86 PSEUDO-CODE
87
88Word16 negate (Word16 var1)
89{
90    Word16 var_out;
91
92    var_out = (var1 == MIN_16) ? MAX_16 : -var1;
93#if (WMOPS)
94    multiCounter[currCounter].negate++;
95#endif
96    return (var_out);
97}
98
99------------------------------------------------------------------------------
100 RESOURCES USED
101   When the code is written for a specific target processor the
102     the resources used should be documented below.
103
104 STACK USAGE: [stack count for this module] + [variable to represent
105          stack usage for each subroutine called]
106
107     where: [stack usage variable] = stack usage for [subroutine
108         name] (see [filename].ext)
109
110 DATA MEMORY USED: x words
111
112 PROGRAM MEMORY USED: x words
113
114 CLOCK CYCLES: [cycle count equation for this module] + [variable
115           used to represent cycle count for each subroutine
116           called]
117
118     where: [cycle count variable] = cycle count for [subroutine
119        name] (see [filename].ext)
120
121------------------------------------------------------------------------------
122*/
123
124
125/*----------------------------------------------------------------------------
126; INCLUDES
127----------------------------------------------------------------------------*/
128#include    "negate.h"
129
130/*----------------------------------------------------------------------------
131; MACROS
132; Define module specific macros here
133----------------------------------------------------------------------------*/
134
135/*----------------------------------------------------------------------------
136; DEFINES
137; Include all pre-processor statements here. Include conditional
138; compile variables also.
139----------------------------------------------------------------------------*/
140
141/*----------------------------------------------------------------------------
142; LOCAL FUNCTION DEFINITIONS
143; Function Prototype declaration
144----------------------------------------------------------------------------*/
145
146/*----------------------------------------------------------------------------
147; LOCAL STORE/BUFFER/POINTER DEFINITIONS
148; Variable declaration - defined here and used outside this module
149----------------------------------------------------------------------------*/
150
151/*----------------------------------------------------------------------------
152; EXTERNAL FUNCTION REFERENCES
153; Declare functions defined elsewhere and referenced in this module
154----------------------------------------------------------------------------*/
155
156/*----------------------------------------------------------------------------
157; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES
158; Declare variables used in this module but defined elsewhere
159----------------------------------------------------------------------------*/
160
161/*----------------------------------------------------------------------------
162; FUNCTION CODE
163----------------------------------------------------------------------------*/
164Word16 negate(register Word16 var1)
165{
166    /*----------------------------------------------------------------------------
167    ; Define all local variables
168    ----------------------------------------------------------------------------*/
169
170    /*----------------------------------------------------------------------------
171    ; Function body here
172    ----------------------------------------------------------------------------*/
173    var1 = (var1 == MIN_16) ? MAX_16 : -var1;
174
175    /*----------------------------------------------------------------------------
176    ; Return nothing or data or data pointer
177    ----------------------------------------------------------------------------*/
178    return (var1);
179}
180